Re: [PATCH-for-9.0 04/10] hw/xen: Factor xen_arch_align_ioreq_data() out of handle_ioreq()

[Philippe Mathieu-Daudé <philmd@xxxxxxxxxx>]

On 13/11/23 19:16, Richard Henderson wrote:
> On 11/13/23 07:21, Philippe Mathieu-Daudé wrote:
> > diff --git a/hw/xen/xen-hvm-common.c b/hw/xen/xen-hvm-common.c
> > index c028c1b541..03f9417e7e 100644
> > --- a/hw/xen/xen-hvm-common.c
> > +++ b/hw/xen/xen-hvm-common.c
> > @@ -426,10 +426,7 @@ static void handle_ioreq(XenIOState *state, 
> > ioreq_t *req)
> >       trace_handle_ioreq(req, req->type, req->dir, req->df, 
> > req->data_is_ptr,
> >                          req->addr, req->data, req->count, req->size);
> > -    if (!req->data_is_ptr && (req->dir == IOREQ_WRITE) &&
> > -            (req->size < sizeof (target_ulong))) {
> > -        req->data &= ((target_ulong) 1 << (8 * req->size)) - 1;
> > -    }
>
> I suspect this should never have been using target_ulong at all: 
> req->data is uint64_t.
This could replace it:

-- >8 --
-    if (!req->data_is_ptr && (req->dir == IOREQ_WRITE) &&
-            (req->size < sizeof (target_ulong))) {
-        req->data &= ((target_ulong) 1 << (8 * req->size)) - 1;
+    if (!req->data_is_ptr && (req->dir == IOREQ_WRITE)) {
+        req->data = extract64(req->data, 0, BITS_PER_BYTE * req->size);
     }
---

Some notes while looking at this.

Per xen/include/public/hvm/ioreq.h header:

#define IOREQ_TYPE_PIO          0 /* pio */
#define IOREQ_TYPE_COPY         1 /* mmio ops */
#define IOREQ_TYPE_PCI_CONFIG   2
#define IOREQ_TYPE_VMWARE_PORT  3
#define IOREQ_TYPE_TIMEOFFSET   7
#define IOREQ_TYPE_INVALIDATE   8 /* mapcache */

  struct ioreq {
    uint64_t addr;          /* physical address */
    uint64_t data;          /* data (or paddr of data) */
    uint32_t count;         /* for rep prefixes */
    uint32_t size;          /* size in bytes */
    uint32_t vp_eport;      /* evtchn for notifications to/from device 
model */
    uint16_t _pad0;
    uint8_t state:4;
    uint8_t data_is_ptr:1;  /* if 1, data above is the guest paddr
                             * of the real data to use. */
    uint8_t dir:1;          /* 1=read, 0=write */
    uint8_t df:1;
    uint8_t _pad1:1;
    uint8_t type;           /* I/O type */
  };
  typedef struct ioreq ioreq_t;

If 'data' is not a pointer, it is a u64.

- In PIO / VMWARE_PORT modes, only 32-bit are used.

- In MMIO COPY mode, memory is accessed by chunks of 64-bit

- In PCI_CONFIG mode, access is u8 or u16 or u32.

- None of TIMEOFFSET / INVALIDATE use 'req'.

- Fallback is only used in x86 for VMWARE_PORT.

--

Regards,

Phil.